CN116087971A - OPA laser radar - Google Patents

OPA laser radar Download PDF

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Publication number
CN116087971A
CN116087971A CN202211692171.6A CN202211692171A CN116087971A CN 116087971 A CN116087971 A CN 116087971A CN 202211692171 A CN202211692171 A CN 202211692171A CN 116087971 A CN116087971 A CN 116087971A
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signal
opa
detection
light source
source module
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Inventor
张磊
徐洋
邓永强
胡攀攀
龚春阳
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Wuhan Wanji Photoelectric Technology Co Ltd
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Wuhan Wanji Photoelectric Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/50—Systems of measurement based on relative movement of target
    • G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

The application provides an OPA lidar comprising: the optical fiber comprises a multi-wavelength light source module, an OPA device, a first beam combiner, a first detection module and a first data processor; the multi-wavelength light source module is used for providing emergent laser beams which are frequency modulation continuous light signals with a plurality of different wavelengths. The OPA device is used for receiving the detection light signal and transmitting the detection light signal to the detection area; and receiving the first echo signal within the detection region. The first echo signal and the reference light signal interfere at the first beam combiner to form a first interference signal. The first detection module is optically connected with the first beam combiner and is used for receiving a first interference signal and converting the first interference signal into a first electric signal; the first data processor is configured to receive and determine probe information within the probe region based on the first electrical signal. Therefore, in the application, only one device of the multi-wavelength light source module is needed to generate a plurality of frequency modulation continuous lights with different center wavelengths, so that the complexity and the cost of the system are reduced.

Description

OPA laser radar
Technical Field
The application belongs to the technical field of laser radar application, and particularly relates to an OPA laser radar.
Background
The laser radar is widely applied to the aspects of automatic driving, 3D printing, virtual reality, augmented reality, intelligent traffic and the like. With popularization of application range, new requirements are also put on performance parameters of the laser radar, such as high frame rate, large field of view, low cost, small volume and the like. In response to the above requirements, optical phased array (Optical phased arrays, OPA) lidars have been developed, however, in OPA lidars, high frame rate, large field of view requirements are to be met, and high sweep frame rate, large sweep range, narrow instantaneous linewidth light sources are necessary. However, the light source currently applied to the OPA laser radar is difficult to meet the requirements, and generally needs to combine laser beams emitted by a plurality of light sources with different wavelengths to be used as the light source of the OPA laser radar, but the system structure of the OPA laser radar comprising the light sources is complex and has high cost.
Disclosure of Invention
In view of this, the embodiments of the present application provide an OPA lidar for solving the problems of complex system and high cost caused by the requirement of multiple light sources in the existing OPA lidar.
An OPA laser radar according to a first aspect of the present embodiment includes a multi-wavelength light source module configured to provide an outgoing laser beam, where the outgoing laser beam is a frequency modulated continuous optical signal having a plurality of different wavelengths; dividing the emergent laser beam into a detection light signal and a reference light signal and outputting the detection light signal and the reference light signal;
the OPA device is optically connected with the multi-wavelength light source module and is used for receiving the detection light signals and transmitting the detection light signals to a detection area; and receiving a first echo signal in the detection area, wherein the first echo signal is formed after the detection signal is reflected by an object to be detected in the detection area;
the first beam combiner is optically connected with the multi-wavelength light source module and the OPA device respectively and is used for receiving the first echo signal and the reference light signal, and the first echo signal and the reference light signal interfere in the first beam combiner to form a first interference signal;
the first detection module is optically connected with the first beam combiner and is used for receiving the first interference signal and converting the first interference signal into a first electric signal;
and the first data processor is electrically connected with the first detection module and is used for receiving and determining detection information in the detection area according to the first electric signal.
In an embodiment, the multi-wavelength light source module includes a light emitting device for generating laser signals having a plurality of center wavelengths and providing the laser signals to a first modulator for modulating the received laser signals having the plurality of center wavelengths to generate the outgoing laser beam.
In an embodiment, the light emitting device comprises any one of a first optical frequency comb generator, an intracavity filter based laser, a nonlinear effect based laser;
the optical frequency comb generator is used for generating an optical frequency comb, and the optical signals emitted by the laser based on the intracavity filtering and the laser based on the nonlinear effect are composed of a plurality of narrow linewidth optical signals with different center wavelengths.
In an embodiment, the multi-wavelength light source module includes a second optical frequency comb generator for directly outputting the outgoing laser beam.
In one embodiment, the first detection module includes a wavelength-division-demultiplexer and a detector array;
the wavelength division multiplexing device is connected with the first beam combiner and the first detection module in a light path respectively and is used for performing wavelength division multiplexing processing on the received interference signals to obtain a plurality of interference sub-signals with different center wavelengths;
the detector array comprises a plurality of first detectors arranged in an array, and each separated interference sub-signal corresponds to at least one first detector.
In an embodiment, the multi-wavelength light source module further includes a beam splitter, where the beam splitter is connected to the multi-wavelength light source module, the first beam combiner, and the OPA device in optical paths, and is configured to split the received optical signal emitted by the multi-wavelength light source into the detection optical signal and the reference optical signal, provide the detection optical signal to the OPA device, and provide the reference optical signal to the first beam combiner.
In an embodiment, the OPA lidar further includes a circulator, where the circulator is connected to the multi-wavelength light source module, the first beam combiner, and the OPA device, and is configured to receive the probe light signal provided by the multi-wavelength light source module and provide the probe light signal to the OPA device, and receive a first echo signal provided by the OPA device and provide the first echo signal to the first beam combiner.
A second aspect of an embodiment of the present application provides an OPA lidar, including:
the first multi-wavelength light source module is used for providing emergent laser beams;
a second multi-wavelength light source module for providing a reference light signal, wherein the outgoing laser beam and the reference light signal are frequency-modulated light signals with a plurality of wavelengths, and the difference of frequencies between adjacent wavelengths in the outgoing laser beam is different from the difference of frequencies between adjacent wavelengths in the reference light signal;
the OPA device is connected with the first multi-wavelength light source module and is used for receiving and transmitting the emergent laser beam to a detection area and receiving a second echo signal in the detection area, wherein the second echo signal is formed after the emergent laser beam in the detection area is reflected by an object to be detected;
the second beam combiner is optically connected with the second multi-wavelength light source module and the OPA device respectively and is used for receiving the second echo signal and the reference light signal, and the second echo signal and the reference light signal interfere in the second beam combiner to form a second interference signal;
the second detection module is connected with the second combination Shu Qiguang and is used for receiving the second interference signal and converting the second interference signal into a second electric signal;
and the second data processor is electrically connected with the second detection module and is used for determining detection information in the detection area according to the second electric signal.
In an embodiment, the first multi-wavelength light source module and the second multi-wavelength light source module are both second optical frequency comb generators.
In an embodiment, the second detection module comprises 1 second detector, the frequency response range of which covers all frequencies in the second interference signal.
Compared with the prior art, the embodiment of the application has the beneficial effects that: the OPA laser radar comprises a multi-wavelength light source module, an OPA device, a first beam combiner, a first detection module and a first data processor; the multi-wavelength light source module is used for providing emergent laser beams which are frequency modulation continuous light signals with a plurality of different wavelengths. The OPA device is optically connected with the multi-wavelength light source module and is used for receiving the detection light signals and transmitting the detection light signals to the detection area; and receiving the first echo signal in the detection region. The first beam combiner is optically connected with the multi-wavelength light source module and the OPA device respectively and is used for receiving a first echo signal and a reference light signal, and the first echo signal and the reference light signal interfere at the first beam combiner to form a first interference signal. The first detection module is optically connected with the first beam combiner and is used for receiving a first interference signal and converting the first interference signal into a first electric signal; the first data processor is electrically connected with the first detection module and is used for receiving and determining detection information in the detection area according to the first electric signal. Because the multi-wavelength light source module can directly output frequency modulation continuous optical signals with different center wavelengths, optical signals with a plurality of different center wavelengths can be generated only by one device with multiple wavelengths, the emergent directions of the optical signals with the plurality of different center wavelengths after being emergent by the OPA device are different, a plurality of emergent light spots can be formed in a detection area, a plurality of positions can be detected at the same time, and the sweep frequency frame rate and the detection precision of the laser radar are greatly improved; in addition, compared with the scheme of combining laser beams emitted by a plurality of light sources in the prior art, the system complexity and cost are reduced by adopting the multi-wavelength light source.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the description of the embodiments or the prior art will be briefly described below.
FIG. 1 is a schematic diagram of an OPA lidar provided in an embodiment of the application;
FIG. 2 is a schematic spectrum of a multi-wavelength light source provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a multi-wavelength light source module according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of a tuned optical frequency comb provided by an embodiment of the present application;
FIG. 5 is a schematic diagram of a probe optical signal and a reference optical signal with frequency modulated continuous wave features provided in an embodiment of the present application;
FIG. 6 is a schematic diagram of an interference signal spectrum provided by an embodiment of the present application;
FIG. 7 is a schematic diagram of an OPA lidar provided in another embodiment of the application;
FIG. 8 is a schematic spectrum of two multi-wavelength light sources provided in an embodiment of the present application;
FIG. 9 is a schematic diagram of demodulating interference signals for multiple center wavelengths provided by an embodiment of the present application;
FIG. 10 is a schematic diagram of an OPA lidar provided in accordance with yet another embodiment of the application;
FIG. 11 is a schematic diagram of an interference signal spectrum corresponding to a distance to be measured of zero according to an embodiment of the present disclosure;
fig. 12 is a schematic diagram of an interference signal spectrum corresponding to a change in a distance to be measured according to an embodiment of the present application.
Fig. 13 is a flowchart of data preprocessing in the two multi-wavelength light source scheme provided in the embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It should be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
In the existing OPA laser radar, in order to obtain a light source with high sweep frame rate, large sweep range and narrow instantaneous line width, a plurality of light sources are generally adopted, and then a wavelength division multiplexer is utilized to perform wave combination on laser beams emitted by the light sources, so that the problems of complex system and high cost are caused. Therefore, the application provides the OPA laser radar, which utilizes the multi-wavelength light source module to provide laser emergent laser beams for the OPA laser radar, wherein the emergent laser beams are frequency-modulated light signals with a plurality of different center wavelengths, the emergent directions of the frequency-modulated light signals with the plurality of different center wavelengths are different after being emergent through the OPA device, a plurality of emergent light spots can be formed in a detection area, and a plurality of positions can be detected simultaneously; therefore, the detection requirements of the laser radar on high frame rate and large view field can be met without wave combination, and the complexity and cost of the system are reduced.
The OPA lidar provided in the present application is exemplified below.
Referring to fig. 1, an OPA lidar according to an embodiment of the present application includes: a multi-wavelength light source module 11, an OPA device 13, a first beam combiner 14, a first detection module 15, and a first data processor 16.
The multi-wavelength light source module 11 is configured to provide an outgoing laser beam, and divide the outgoing laser beam into a detection light signal and a reference light signal, and output the detection light signal and the reference light signal, where the outgoing laser beam is a frequency modulated continuous light signal with a plurality of different wavelengths, and the frequency modulated continuous light signal may be a frequency modulated continuous light signal with a narrow linewidth.
The OPA device 13 is optically connected with the multi-wavelength light source module 11, and is used for receiving the detection light signal and transmitting the detection light signal to the detection area; the OPA device 13 also receives a first echo signal in the detection area, wherein the first echo signal is formed after reflection of the detection signal in the detection area by the object to be detected.
The first beam combiner 14 is optically connected to the multi-wavelength light source module 11 and the OPA device 13, and is configured to receive the first echo signal and the reference light signal, where the first echo signal and the reference light signal interfere to form a first interference signal.
The first detection module 15 is optically connected to the first beam combiner 14, and is configured to receive the first interference signal and convert the first interference signal into a first electrical signal.
The first data processor 16 is electrically connected to the first detection module 15 for receiving and determining detection information in the detection area from the first electrical signal.
The optical connection may be optical fiber connection, or may be spatial optical path or waveguide connection. In practical applications, the multi-wavelength light source module is not typically disposed on an optical chip, and the outgoing laser beam provided by the multi-wavelength light source module may be coupled into an OPA device on the optical chip through an optical fiber and an input coupler. The optical path connection is generally realized through a waveguide between the optical chip and each device integrated on the optical chip.
Specifically, the OPA device includes an input coupler, a phase modulator and an optical antenna, and the phase of the detection optical signal can be adjusted by adjusting the phase modulator in the OPA device 13, so that the detection optical signal is directed to different lateral positions of the detection area, thereby realizing the lateral scanning of the detection area by the detection optical signal. By manufacturing a grating antenna on the internal waveguide of the OPA device 13 and/or adjusting the central wavelength of the detection optical signal, the detection optical signal can be emitted to different longitudinal positions, so as to realize longitudinal scanning of a detection area; when longitudinal scanning is achieved by adjusting the wavelength, the longitudinal scanning range is positively correlated with the wavelength range of the probe optical signal, thereby achieving two-dimensional scanning. The data processor 16 parses the interference signal to determine the difference between the reference light signal and the reflected light signal reflected by the detection area, and thus to determine the detection information within the detection area. The detection information in the detection area may include information such as distance, speed, and reflectivity of the object in the detection area.
The laser beam emitted by the multi-wavelength light source module 11 is a frequency modulation continuous light signal with a plurality of different wavelengths, so that the narrow linewidth frequency modulation continuous light with a plurality of different center wavelengths can be generated only by one device of the multi-wavelength light source module, the emergent directions of the light signals with a plurality of different center wavelengths after being emergent through the OPA device are different, a plurality of emergent light spots can be formed in a detection area, a plurality of positions in the longitudinal direction can be detected at the same time, further, the two-dimensional scanning of the detection area is realized, the sweep frame rate and the detection precision of the laser radar are greatly improved, the detection requirements of the OPA laser radar on high frame rate and large visual field are met, compared with the scheme of combining laser beams emitted by a plurality of light sources, the number of devices is reduced by adopting the multi-wavelength light source module, the complexity of the light path design is reduced, and the complexity and the cost of the system are further reduced.
In addition, if a single large-range tunable laser is used to detect the optical signals, in order to realize two-dimensional scanning of the detection area, the optical signals of the respective center wavelengths need to be scanned one by one. If the detection field of view is larger, the corresponding wavelength scanning range is synchronously increased, the scanning frame rate of the OPA laser radar is reduced due to large-range scanning, and the manufacturing difficulty of the large-range tunable light source is also larger. The multi-wavelength light source module can generate a plurality of frequency modulation continuous optical signals with different center wavelengths, which is equivalent to the generation of a plurality of optical signals with smaller scanning range, and the optical signals with different center wavelengths can be synchronously scanned, so that the detection by adopting the multi-wavelength light source module can also improve the measurement frame rate of the OPA laser radar.
The spectral structure of the multi-wavelength light source is shown in fig. 2, each wavelength has a different center frequency and is mutually discrete, and the line width of each wavelength is narrow, which can reach hundreds kHz or even narrower. The frequency interval between adjacent wavelengths is a fixed value and can be designed and adjusted according to the requirements. The spectrum coverage of the multi-wavelength light source can reach hundred nm magnitude or even octave, so that the measuring range of the OPA laser radar can be improved.
The multi-wavelength light source module for outputting the frequency modulation continuous light signals with different center wavelengths can be obtained by various modes and various materials, for example, a laser can be used as the multi-wavelength light source module by modulating the loss in the laser cavity, and the light signals with different center wavelengths are output. The optical signal is processed through a nonlinear process (e.g., four-wave mixing, stimulated brillouin scattering), and a multi-wavelength light source that outputs a plurality of discrete center wavelengths can also be obtained.
In one embodiment, as shown in fig. 3, the multi-wavelength light source module 11 includes a light emitting device 111 and a first modulator 112, the light emitting device 111 is used to generate laser signals having a plurality of center wavelengths and provide the laser signals to the first modulator 112, and the first modulator 112 is used to modulate the received laser signals having the plurality of center wavelengths to generate outgoing laser beams. That is, the frequency of the laser signal corresponding to each center wavelength in the laser signals generated by the light emitting device in this embodiment is fixed, and therefore, the laser light signal output by the multi-wavelength light source module needs to have the characteristic of a frequency modulated continuous wave by an external modulation method. The first modulator 112 modulates the laser signal, including dynamically adjusting the frequency of the laser signal, so that the optical signal output by the multi-wavelength light source module can realize synchronous frequency scanning of different wavelengths on the premise of ensuring multiple wavelengths.
In an embodiment, the light emitting device 111 comprises any one of a first optical frequency comb generator for generating an optical frequency comb, an intra-cavity filter based laser, and a nonlinear effect based laser, the optical signal emitted by the intra-cavity filter based laser or the nonlinear effect based laser being composed of a plurality of narrow linewidth optical signals of different center wavelengths.
The optical frequency comb, the laser based on intra-cavity filtering and the optical signal emitted by the nonlinear laser have narrower instantaneous linewidth relative to other forms of frequency-modulated optical signals comprising a plurality of center wavelengths, so that the OPA laser radar can detect a detection area with longer distance.
The optical frequency comb can be a microcavity optical frequency comb or an electrical modulation optical frequency comb. The microcavity optical frequency comb is an optical frequency comb generated by a mode of a micro-ring cavity, a micro-sphere cavity, a micro-disk cavity or a micro-column cavity based on materials such as silicon, silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, lithium niobate, calcium fluoride, aluminum gallium arsenide, gallium phosphide, magnesium fluoride and the like. An electrically modulated optical frequency comb is an optical frequency comb produced based on a combination of intensity modulators, phase modulators of different structures, different materials. In this embodiment, an optical frequency comb is selected as the light emitting device because the optical frequency comb has a narrower instantaneous line width, and the detection distance of the laser radar can be increased.
In another embodiment, the multi-wavelength light source module includes a second optical frequency comb generator for directly outputting an outgoing laser beam, which is an optical frequency comb having a frequency modulated continuous wave characteristic, through internal modulation. Wherein, the internal modulation can be to change the frequency or wavelength of the pump light in the process of generating the optical frequency comb by the optical frequency comb generator, so that the output optical frequency comb has the characteristic of frequency modulation continuous wave. Wherein the frequency of the pump light can be adjusted by adjusting the injection current.
As shown in fig. 4 (a), the frequency is f k When the frequency of the pumping light is tuned, synchronous scanning can be realized in other frequency bands (i.e. comb teeth), namely, the frequency of the optical signal output by the optical frequency comb generator can be adjusted by adjusting the frequency of the pumping light, so as to obtain a multi-wavelength light source with frequency modulation continuous wave characteristics (as shown in (b) of fig. 4, three signals f with different center wavelengths l 、f k 、f m Time-dependent frequency of the optical frequency comb generator) so as to realize different waves on the premise of outputting multiple wavelengthsLong synchronous frequency sweeps.
When the multi-wavelength light source module with the frequency modulation continuous wave characteristic detects, the corresponding reflected light signal and the reference light signal are shown in fig. 5, and the interference signal frequency after the interference of the reflected light signal and the reference light signal is shown in fig. 6. By resolving the interference signal, the distance and speed of the target within the detection zone can be determined. Specifically, the frequencies of the interference signals of the rising edge and the falling edge in the same modulation period in the interference signals are set to be f respectively b And f a The distance D and the moving speed v of the object to be measured can be obtained by the method respectively as follows:
Figure BDA0004021696270000091
wherein c represents the speed of light in vacuum, B represents the modulation bandwidth of the FM continuous wave, T represents the modulation period of the FM continuous wave, lambda 1 Representing the center wavelength of the fm continuous wave.
In one embodiment, as shown in fig. 1, the OPA device 13 has a number of 1, and the OPA lidar further includes a circulator 12, where the circulator 12 is connected to the multi-wavelength light source module 11, the first beam combiner 14, and the OPA device 13 in an optical path, and is configured to receive a probe light signal provided by the multi-wavelength light source module 11 and provide the probe light signal to the OPA device 13, and receive a first echo signal provided by the OPA device 13 and provide the first echo signal to the first beam combiner 14. Namely, by providing a circulator, the probe optical signal and the reflected optical signal share one OPA device.
In another embodiment, the number of OPA devices is 2, one of the OPA devices is optically connected to the multi-wavelength light source module 11, and the other OPA device is optically connected to the first beam combiner 14. The probe optical signal is directed to the probe region through one of the OPA devices and the reflected optical signal is directed to the first combiner 14 through the other OPA device.
Reflected light signals corresponding to the detection light signals with different center wavelengths are overlapped and interfered with the reference light signals in time in the first beam combiner. In an embodiment, as shown in fig. 7, the first detection module includes a wavelength division demultiplexer and a detector array, where the wavelength division demultiplexer is connected to the first beam combiner and the first detection module in optical paths respectively, and is configured to perform wavelength division demultiplexing on the received interference signal to obtain a plurality of interference sub-signals with different center wavelengths. The detector array includes a plurality of first detectors arranged in an array, each of the separated interferometric sub-signals corresponding to at least one of the first detectors.
For example, the multi-wavelength light source module includes n detection light signals with different center wavelengths, and the wavelength demultiplexing device performs wavelength demultiplexing processing on the interference signals after obtaining the interference signals corresponding to the detection light signals, so as to obtain interference sub-signals with different center wavelengths. The OPA laser radar corresponds and includes detector 1, detector 2, n detector altogether, and the interference signal that every detector received in n detectors is the interference sub-signal of different center wavelength to can detect the reflection light signal of each center wavelength alone, and then can distinguish the detection signal of different detection position, obtain the detection information of detection region different positions, realize the accurate detection to each position of detection region.
Illustratively, as shown in fig. 8 (a) and 8 (b), the frequency modulation ranges of the 3 detection light signals are f, respectively 01 +f 1 To f 01 +f 2 、f 02 +f 1 To f 02 +f 2 F 03 +f 1 To f 03 +f 2 The reflected light signal (fig. 8 (a) is a solid line) and the reference light signal (fig. 8 (b) is a broken line), and then an interference signal (fig. 8 (b)) is generated, and each detector receives an interference sub-signal corresponding to the center wavelength. The data processor analyzes each interference sub-signal to obtain the signal frequencies of the rising edge and the falling edge corresponding to each interference sub-signal with the central wavelength, wherein the signal frequencies are respectively as follows: f (f) a1 ，f b1 ；f a2 ，f b2 ；f a3 ，f b3 . For each interference sub-signal with the center wavelength, the detection information corresponding to the corresponding reflected light signal can be obtained according to the signal frequencies of the rising edge and the falling edge and the formula 1.
In one embodiment, the multi-wavelength light source module includes 1 multi-wavelength light source, and the optical signals emitted from the 1 multi-wavelength light source are divided into a detection optical signal and a reference optical signal. As shown in fig. 7, the OPA lidar may further include a beam splitter, which is connected to the multi-wavelength light source module, the first beam combiner, and the OPA device in optical paths, respectively, for dividing the received optical signal emitted by the multi-wavelength light source into a detection optical signal and a reference optical signal, and providing the detection optical signal to the OPA device, and providing the reference optical signal to the first beam combiner. The beam splitter divides an optical signal emitted by a multi-wavelength light source into a detection optical signal and a reference optical signal, and meanwhile, the energy of the detection optical signal and the energy of the reference optical signal can be reasonably distributed according to the application scene of the OPA laser radar.
In one embodiment, as shown in fig. 9, the OPA lidar includes a first multi-wavelength light source module 91, a second multi-wavelength light source module 92, an OPA device 93, a second beam combiner 94, a second detection module 95, and a second data processor 96.
The first multi-wavelength light source module 91 is used for emitting laser beams, and the second multi-wavelength light source module 92 is used for providing reference light signals. The outgoing laser beam is also a detection light signal, the outgoing laser beam and the reference light signal are both frequency modulated light signals with a plurality of wavelengths, and the difference in frequency between adjacent wavelengths in the outgoing laser beam is different from the difference in frequency between adjacent wavelengths in the reference light signal. Wherein the amount of variation in the difference between the adjacent center wavelengths of the two multi-wavelength light sources is related to the detection scene, e.g., the farther the detection distance is, the greater the amount of variation in the difference between the adjacent center wavelengths of the two multi-wavelength light sources is.
The OPA device 93 is connected to the first multi-wavelength light source module 91, and is configured to receive and transmit the outgoing laser beam to the detection area, and receive a second echo signal in the detection area, where the second echo signal is formed after the outgoing laser beam in the detection area is reflected by the object to be detected.
The second beam combiner 94 is optically connected to the second multi-wavelength light source module 92 and the OPA device 93, respectively, and is configured to receive the second echo signal and the reference light signal, where the second echo signal and the reference light signal interfere in the second beam combiner 94 to form a second interference signal.
The second detection module 95 is optically connected to the second beam combiner 84, and is configured to receive the second interference signal and convert the second interference signal into a second electrical signal.
The second data processor 96 is electrically connected to the second detection module 95 for determining detection information in the detection area based on the second electrical signal.
In an embodiment, the first multi-wavelength light source module and the second multi-wavelength light source module are both second optical frequency comb generators. The second optical frequency comb generator is used for directly outputting outgoing laser beams through internal modulation, and the outgoing laser beams are optical frequency combs with frequency modulation continuous wave characteristics.
In one embodiment, the OPA device 93 has a number of 1, and the OPA lidar further includes a circulator 97, where the circulator 97 is optically connected to the first multi-wavelength light source module 91, the second beam combiner 94, and the OPA device 93, and is configured to receive the outgoing laser beam provided by the first multi-wavelength light source module 91 and provide the outgoing laser beam to the OPA device 93, and receive the second echo signal provided by the OPA device 93 and provide the second echo signal to the second beam combiner 94.
Illustratively, as shown in fig. 10, the waveforms of the first and second multi-wavelength light source modules are similar but the wavelength discrete positions are different. For example, the first and second multi-wavelength light source modules each have a plurality of discrete wavelengths, and the initial wavelengths of the two multi-wavelength light sources are the same, e.g., λ 11 And lambda is 21 The same, but the frequency spacing between adjacent center wavelengths is fixed and different, with the difference being Δf. Thus, from the initial wavelength, the difference between adjacent center wavelengths of the first and second multi-wavelength light sources is 0, Δf,2Δf, …, nΔf in order. By adopting the mode, the principle of frequency division multiplexing can be adopted at the detection end, namely, interference signals with different center wavelengths are measured by adopting different frequency parts of the detector, synchronous detection of the interference signals with different center wavelengths can be realized, and detection information of different positions of a detection area can be obtained by adopting only one detector.
For example, as shown in FIG. 11, the frequencies of the discrete wavelengths of the multi-wavelength light source as the detection light signal are f 01 ，f 02 ，…，f 0n The frequencies of the discrete wavelengths of the multi-wavelength light source as the reference light signal are f 01 、f 02 +Δf，…，f 0n ++ (n-1) Δf, realizing a sweep frequency range f of the probe optical signal after frequency modulation 0n +f 1 To f 0n +f 2 The sweep frequency range of the reference optical signal is f 0n +(n-1)Δf+f 1 To f 0n +(n-1)Δf+f 2 . The detection light signal is reflected by the detection area to obtain a reflected light signal, and when the distance to be detected is 0, the frequencies of interference signals of the reflected light signal and the reference light signal are respectively 0, deltaf, 2 deltaf and …, (n-1) deltaf. Therefore, by adopting the wavelength division multiplexing principle, interference signals with different center wavelengths are measured by adopting different frequency parts of the detector, and single-point measurement of the interference signals with all the center wavelengths can be realized.
In one embodiment, the second detection module 95 includes 1 second detector, and the frequency response range of the second detector covers all frequencies in the second interference signal, so that the detection of all interference signals can be achieved by one second detector. The second data processor 96 is configured to determine detection information of the detection light signal corresponding to the center wavelength according to the interference signal of the preset frequency band.
For example, as shown in fig. 12, taking 3 detection light signals as an example, the frequency ranges of the 3 detection light signals are f respectively 01 +f 1 To f 01 +f 2 、f 02 +f 1 To f 02 +f 2 F 03 +f 1 To f 03 +f 2 . And 3 interference signals with different center wavelengths are obtained by adjusting the distance to be detected or the introduction speed of the detection light signals with the center wavelengths, and the frequency spectrums of the 3 interference signals are distributed in different frequency bands. The signal frequencies of the rising edge and the falling edge in the same modulation period corresponding to the 3 interference signals are f respectively a1 ，f b1 ，Δf+f a2 ，Δf+f b2 ，2Δf+f a3 ，2Δf+f b3 . The data analyzer analyzes the interference signals of different frequency bands, and obtains the detection of each center wavelength according to the signal frequencies of the corresponding rising edge and the corresponding falling edge and the formula 1Detection information corresponding to the optical signal. Therefore, the synchronous detection of the distance and the speed of different positions of the detection area can be realized by only carrying out single-point test on one detector without a wavelength demultiplexing process, and the system complexity and the cost of the OPA laser radar are further reduced.
In one embodiment, in the case of resolving the distance and velocity by means of equation 1, the interference signal is preprocessed, and the data preprocessing flow is shown in fig. 13. Firstly, determining the difference value of the frequency difference between the adjacent central wavelengths of two multi-wavelength light sources according to the parameters of a first multi-wavelength light source and the parameters of a second multi-wavelength light source, and carrying out Fourier transform on the measured interference signals to obtain frequencies corresponding to the rising edge and the falling edge of the interference signals; then, dividing the frequency of the interference signal by taking the difference value delta f as a reference, wherein the divided frequency ranges are 0-delta f, delta f-2 delta f and …, (n-1) delta f-n delta f in sequence; the initial values of the corresponding frequency bands are respectively subtracted from the signal frequencies in the divided frequency bands to obtain real frequencies, and if the frequency of the interference signal is in the (m-1) delta f-m delta f frequency band, the signal frequency needs to be subtracted by (m-1) delta f to obtain the real frequencies. And simultaneously determining the frequency bands, and synchronously determining the central wavelengths or the spatial positions corresponding to different frequency bands. The obtained true signal frequency is then substituted into formula 1 to obtain corresponding measurement information. As shown in fig. 12, the signal frequencies of the rising and falling edges calculated by substituting equation 1 among the 3 interference signals are f a1 、f b1 ，f a2 、f b2 ，f a3 、f b3 。
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.

Claims (10)

1. An OPA lidar, comprising:
the multi-wavelength light source module is used for providing emergent laser beams which are frequency modulation continuous optical signals with a plurality of different wavelengths; dividing the emergent laser beam into a detection light signal and a reference light signal and outputting the detection light signal and the reference light signal;
the OPA device is optically connected with the multi-wavelength light source module and is used for receiving the detection light signals and transmitting the detection light signals to a detection area; and receiving a first echo signal in the detection area, wherein the first echo signal is formed after the detection signal is reflected by an object to be detected in the detection area;
the first beam combiner is optically connected with the multi-wavelength light source module and the OPA device respectively and is used for receiving the first echo signal and the reference light signal, and the first echo signal and the reference light signal interfere in the first beam combiner to form a first interference signal;
the first detection module is optically connected with the first beam combiner and is used for receiving the first interference signal and converting the first interference signal into a first electric signal;
and the first data processor is electrically connected with the first detection module and is used for receiving and determining detection information in the detection area according to the first electric signal.
2. The OPA lidar according to claim 1, wherein the multi-wavelength light source module comprises a light emitting device for generating laser signals having a plurality of center wavelengths and providing the laser signals to the first modulator, and a first modulator for modulating the received laser signals having the plurality of center wavelengths to generate the outgoing laser beam.
3. The OPA lidar according to claim 2, wherein the light emitting device comprises any one of a first optical frequency comb generator, an intracavity filter based laser, a nonlinear effect based laser;
the optical frequency comb generator is used for generating an optical frequency comb, and the optical signals emitted by the laser based on the intracavity filtering and the laser based on the nonlinear effect are composed of a plurality of narrow linewidth optical signals with different center wavelengths.
4. The OPA lidar according to claim 1, wherein the multi-wavelength light source module comprises a second optical frequency comb generator for directly outputting the outgoing laser beam.
5. The OPA lidar of claim 1, wherein the first detection module comprises a wavelength-division-demultiplexer and a detector array;
the wavelength division multiplexing device is connected with the first beam combiner and the first detection module in a light path respectively and is used for performing wavelength division multiplexing processing on the received interference signals to obtain a plurality of interference sub-signals with different center wavelengths;
the detector array comprises a plurality of first detectors arranged in an array, and each separated interference sub-signal corresponds to at least one first detector.
6. The OPA lidar according to claim 1, wherein the multi-wavelength light source module further comprises a beam splitter, which is optically connected to the multi-wavelength light source module, the first beam combiner, and the OPA device, respectively, for dividing the received optical signal emitted by the multi-wavelength light source into the probe optical signal and the reference optical signal, and providing the probe optical signal to the OPA device, and the reference optical signal to the first beam combiner.
7. The OPA lidar according to claim 1, further comprising a circulator in optical communication with the multi-wavelength light source module, the first beam combiner, and the OPA device, respectively, for receiving the probe light signal provided by the multi-wavelength light source module and providing the probe light signal to the OPA device, and for receiving the first echo signal provided by the OPA device and providing the first echo signal to the first beam combiner.
8. An OPA lidar, comprising:
the first multi-wavelength light source module is used for providing emergent laser beams;
a second multi-wavelength light source module for providing a reference light signal, wherein the outgoing laser beam and the reference light signal are frequency-modulated light signals with a plurality of wavelengths, and the difference of frequencies between adjacent wavelengths in the outgoing laser beam is different from the difference of frequencies between adjacent wavelengths in the reference light signal;
the OPA device is connected with the first multi-wavelength light source module and is used for receiving and transmitting the emergent laser beam to a detection area and receiving a second echo signal in the detection area, wherein the second echo signal is formed after the emergent laser beam in the detection area is reflected by an object to be detected;
the second beam combiner is optically connected with the second multi-wavelength light source module and the OPA device respectively and is used for receiving the second echo signal and the reference light signal, and the second echo signal and the reference light signal interfere in the second beam combiner to form a second interference signal;
the second detection module is connected with the second combination Shu Qiguang and is used for receiving the second interference signal and converting the second interference signal into a second electric signal;
and the second data processor is electrically connected with the second detection module and is used for determining detection information in the detection area according to the second electric signal.
9. The OPA lidar of claim 8, wherein the first multi-wavelength light source module and the second multi-wavelength light source module are each a second optical frequency comb generator.
10. The OPA lidar of claim 8, wherein the second detection module comprises 1 second detector, and wherein a frequency response range of the second detector covers all frequencies in the second interference signal.
CN202211692171.6A 2022-12-28 2022-12-28 OPA laser radar Pending CN116087971A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116931002A (en) * 2023-09-07 2023-10-24 深圳市速腾聚创科技有限公司 Laser radar and mobile device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116931002A (en) * 2023-09-07 2023-10-24 深圳市速腾聚创科技有限公司 Laser radar and mobile device
CN116931002B (en) * 2023-09-07 2023-12-29 深圳市速腾聚创科技有限公司 Laser radar and mobile device

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